Search For An HIV Vaccine May Go Through The Cow

According to a July study done by the Scripps Research Institute, the process in which cows create antibodies could be a key step in developing a vaccine against HIV, the virus that develops into AIDS for millions of humans across the Earth. According to the study, when injected with viral proteins, cows are capable of producing antibodies that are able to block HIV infection. More specifically, the scientists injected four cows with a protein that mimics HIV and proceeded to isolate antibodies created by the cows over the course of a year. The scientists then further tested the antibodies to see if they were capable of blocking HIV from infecting cells.

The main concern scientists have run into when developing vaccines against HIV is that the virus mutates constantly, which makes it so that any successful vaccine has to prevent against a myriad of strains. The human immune system on its own does not usually create such broadly neutralizing antibodies. However, Scripps has noticed that these necessary broadly neutralizing antibodies are usually long and gangly, a description that applies to the antibodies normally created by cows.

The scientists were particularly surprised by how quickly the cows were able to produce the adequate amount of antibodies. Within two months, all the cows involved in the study were able to produce antibodies that blocked a wide variety of viral strains. They were also able to suppress the virus with lesser doses than human antibodies would require. “We definitely didn’t expect to get the response that we did. We didn’t expect the extent of the response or how quick the response developed. That was kind of mind-blowing,” was how Devin Sok, director for antibody discovery and development at the International AIDS Vaccine Initiative, described his reaction to the results.

As for an explanation on just why cows are able to do this when humans currently aren’t, Dr. Vaughn Smider points to the uniqueness of the cow’s stomach as a potential source. Smider, who is a professor of molecular medicine for Scripps, says that the cow’s stomach’s large capacity contributes to the strength of its immune system. A cow’s stomach can hold as much as 20 gallons of digestive microbes, and is shaped in such a way that its antibodies need to be longer than human antibodies in order to reach the stomach’s grooves and crevices. “The cow immune system has to deal with keeping in check all these microorganisms,” Smider says.

While the headlines may call this a massive breakthrough, experts in the field caution that this is only a small step in the quest for creating an HIV vaccine. As Dr. John Mascola, director of vaccine research at the National Institute of Allergy and Infectious Diseases, explains: “The study… doesn’t tell us how to make a vaccine for HIV in people, but it does tell us how the virus evades the human immune response.” Mascola also highlights the importance of using cows to develop an envelope that most closely represents HIV so that vaccine tests in the future can be as accurate as possible.